operate in enclosed canals. The device includes a main chassis and a swivel head attached by means of a rotatable arm and/or a vertically adjustable boom (manipulator arm) to the face of this main chassis. The device is equipped with wheels both above and below the main chassis.
Preferably, the device is fitted with a head that is suitable for sand blasting the inner surfaces of closed canals. The head can, however, be fitted with an optical appliance, a gamma-ray radiator, a paint spray gun, an air-cleaner nozzle or with similar equipment, where it is important that, during the forward movement of the vehicle, the head maintains a prescribed distance from the inner surfaces of the canal being traversed.
The European Application No. A-99 819 discloses a self-propelled vehicular device which is intended for operation in enclosed canals that cannot be approached by human beings (in this instance, the canals of atomic reactor facilities). The device has a central chassis to which are attached two rollers below and two others above the chassis. The front part of the chassis is bent forward over the lower rollers and thus achieves a detecting position, so that a detector mounted thereon can be moved along the floor of the canal. BY adjusting the angle of the bent chassis and by means of a slight twisting, a certain maneuverability of the detector is possible. The vehicle is maintained in this position by means of two upper rollers, one of which lies b.RTM.hind the other along the axis of motion. These upper rollers, which move along the ceiling of the canal, are mounted on two spring-loaded arms interlocked with each other.
The disadvantage of this prior known vehicle is that the central chassis can achieve a particular average distance from the floor of the canal which is determined by the lower rollers. It is true that the upper rollers make possible a degree of control by pressure on the detector. However, allowances for the diameter of the canal cannot generally be made and an adjustment of the main chassis in relation to the center of the canal is not intended or possible.
In order to create a vehicular device for operating in, inspecting, cleaning or sand blasting narrow canal inner surfaces, flat surfaces, ducts or other enclosed cavities which are difficult to pass or to reach, the device must be so designed that the main chassis can be adjusted to the exact midpoint between the upper and lower canal wall. By this is meant for example, canal tubes, aircraft air-intakes, gaseous smoke ducts and such objects whose tubes and gullies display a differing diameter along their length.
Up until now, such canals were cleaned by persons who had to crawl into the canals. Such persons had to be completely enveloped in special suits and supplied from without with air to breathe. This activity was strenuous and posed extraordinary threat to health which could not be reasonably expected of any person over a long Period of time.